Carburetor



June 15 1926. 1,589,175

A. s. HODGSON CARBURETOR Filed Nov. 16, 1925 5 Sheets-Sheet 4 A LGEQTHovow 1, ma@ www, l Ms* lime 15 ,1926.

5.. 7 t l 9, n 8 few 5, .1.. i h. s 5 y m m w f R D, m w l. ov m d H U vM, m S A v C d :L sllslf A m c j Jlnluuilllnnnn UNM. l .V\"\\ Y /NvE/wm;V Asav Q Hooegm v. A 1 Siu# MMM Patented June l5, 1926.

UNITED STATES ALBERT SEPTIMUS HoDGsoN,

or FARNBOROUGH, ENGLAND.

CARBURETOR.

'I Application led. November 16, 1925,. Serial No. 69,484, and in GreatBritain May 21, 1924.

This invention relates to; carburetors for Internal combustion engines,and the object is toprovide an improved construction of carburetor inwhich fthe interior of the throttle chamber is divided solas to form anexpansion chamber into which the fuell is admitted,v and a diffuserchamber into which the fuel then passes and where itis mixed .withauxiliary air before passing out through aspiratingports; in which thesaid supply of auxiliary air is diminished as the mainsupply past thethrottle is increased; in which the fuel is led to the expansion chamberthrough a depression chamber hav- 5 ing a controllable opening to theatmosphere;

in which the said controllable openingmay be automatically controlled sothat the proportion of fuel to air may be varied automatically andmaintained constant for various speeds and extent. of throttle opening;in which eddies and turbulences in the air stream through the carburetormay be eliminated; in lwhich an auxiliary supply of rich and highly'atomized mixture may be supplied to the engine when it is desired tostart from cold; and in which the connection between the carburetorcasing and the fuel supply chamber shall permit' of a vertical,horizontal, or inclined disposition of the said casing.

Theninvention is illustrated in the accompanyingA drawings, in whichFigure l is a vertical sectional View mainly on the line I-I of Fig. 2.

Fig. 2 is a sectional view on the line Il, II of Fig. l.

Figs. 2^ and 2B are detail views of'an automatic control device.

Figs. 3 and lare, respectively` a sidey elevation and a plan view butare drawn to a smaller scale.

Figs. 5 to 7 show the general arrangement of what is substantially thearrangement illustrated in Figs. 1, 3 and 4 but with the carburetorcasing turned, relativelyto the float chamber, through90 degrees fromthe position shown inthe latter figures.

Fig. 5 is a plan view in section on the line V, V of Fig. 7. y

Fig. 6 is a view corresponding to 5, but. with one half of thecarburetor casing, and the float chamber in plan.

Fig. 7 is a section onthe line VII, VII

* of Fig. 5. and

Fig. 8 is a section on the line VIII, VIII 0f Fig. 7..V

A is the carburetor casing near the forward end of which a bulbous chokecore a1 is carried by r-ib a2, the interior of the casing 1n proximityto the core being preferably curvilinear so as to follow the contour ofon the flange c2 ofthe float chamber C in `which the float c is located;the depression chamber B in turn Vcommunicates through a nozzle b1, a.passage-way b2, fuel jet D and passage-way b3 see Fig. l) with the fioatchamber supplied with fuel through a` con-- duit controlled by a oatvalve. Branching off from the passageway b2 at a point between the fueljet D and the'depression chamber` B are two passage-ways e and f*leading to devices to be described later.

The core a3 is provided with a fiange al between which andthefplane rearface of they choke core is ripped an internal flange of a fixed hollowcylindricalguide a6 concentrically arranged within the bore ofthe maincarburetor casing. At the rear end of the carburetor casing (thelowermost end in the vertical arrangement) is a nxed centrally locatedhollow boss a7 carried by webs or ribs from the main casing.

A. control rod g1 which carries the throttle K, K', has its rear endturned so as to be a sliding fit in the bore of a sleeve a8 carried bythe hollow boss a7 carried from the ring alo by the. rib a9, the lowerend of the sleeve as being turned to fit the bore of the. boss a7 andhaving a collar which bears on the said boss al, the sleeve and bossbeing cut away at a point opposite the rib ai to accommodate theactuating lever e2; this rod g1 is adapted to be moved axially in anvsuitable manner, preferably by a ball-headed lever g2 engaglng with aslot in the rear end of the rod; the said lever being. fixed to atransverse shaft G journalled in suitable bearings carried by the ring afixed to the casing A, the said shaft also carrying an actuating leverg5 adapted to be operatedby the driver in any convenient manner; angularmovement imparted to the shaft G imparts axlal movement to the lcontrolrod and throttle. The

sleeve a8, carried by the hollow boss al, is threaded and carries afixed tubularfmember H which will be termed the fixed tapered member,the rear exterior configuration 71.1 of which is conical. To the'interior of the main casing, at a point, say, a little in rear yof thecentre of its length is fitted a I fixed ring a the interior surface of.which is formed by reversely set cones; this ring which provides aventuri-like constriction. of the bore of the main casing will beAtermed the Venturi member.

The throttle takes the form of a casing K, K, having an inner` part K,connected. to the outer'part K, and being attached by the screw 7c3 to,and moving axially with the control rod g1; at its forward end k1 thepart K is of cylindrical configuration, its

.bore sliding on and being guided and supported by the exterior of thefixed cylin.- drical guide a". The rear end k2 of the partK is ofconical configuration; and cooperates .with the valve seat formed by theconstricted part am of the bore of the Venturi member, closing the -saidbore when thethrottle is in its extreme rearward position, (see Fig. l).Internally the said coned part/c2 of the throttle acting in cooperationwiththe coned part h1 of the fixed taper member H, serves, when axialmovement is imparted to the throttle, to control the admission of airtothe interior of the throttle through the open rear end thereof. Aspiral spring S is fitted in the throttle which tends to move the latterrearwardly.

Through the throttle ports c* and fc5 are formed, the latter h5, at thatpart of the throttle which acts as a valve for the venturi constrictionam, and the former 7c", in the part K.

Fuel from the duct (114 in the choke core.

enters the space g within the sleeve a and the throttle and passesthrough the ports la* into the part Q which will be termed the diffuserchamber. Then the throttle is partly open the movement of the air drawn,by the action of the engine suction, through the open rear end of themain casing past the venturi-like constriction` causesan aspiratingactlon on the throttle ports 105;

this induces the flow of fuel through the de` pression chamber B,passage-way a4, chamber Q. and ports kt into the diffuser4 chamber Q.which under normal running conditions has been previously mixed withair, as hereinafter described; the aspirating actionalso induces theflow of air into the diffuser chamber through the end of the throttlesleeve. l

.The axial movement of the throttle by varyingthe venturi-likel openingcontrols the admlsson of main au: past the thrcttle and `therefore thedegree of the aspirating action on the throttle ports h5 andthe saidaxial movement also simultaneously controls' by co-operation of theconed end vof the throttle with the tapered part h1 ofthe fixed `nemberH, the admission of air tothe beingv closed by the plate 015 in whichisformed the needle valve seat cB controlled by the needle valve o9.Fuel entering by o3 'passes through the ports c1", thence through thegauze 07 into the chamber cu, formed by the partition plate 015 whichabuts the plate 015 and the packing washer c", from which chamber itpasses through ports 012 and the seat 08 into the fuel chamber, to aheight determined by the position of the fioat c; the float operatingthe needle valve by engaging the bulbous ends of arms c pivoted at 02,the other ends of which armsA engage the sleeves c14 fixed to the fuelvalve. The cover C of the fioat chamber is held in closed position bythe pivoted spring 015 as shown in Fig. 4.

The fuel from the fioat chamber after passing through the nozzle D,passes up the passage-way bzvto the depression chamber B, and can alsopass through the respective branch passage-ways e1 and f1 to a primingdevice E, and to a fuel-ratio correcting 'device F. Fuell is admitted tothe device F to fill up the tube or passageway f1 for a purpose laterset forth. The priming device comprises a tube E fitting in a verticallos l bore formed in part of the float casing C.v located between'thefioat chamber and the carburetor, the lower end e2 ofv the tube'isscrew-threaded Aand fits the lower screwthreaded end of the bore so thatthe passageway e1 communicates with a calibrated opening e3 formed atthe lower end of the tube. y

The tube E is provided with a port el which .is vpreferably taperedvcircumferentially as shown in Fig. 2, which :port aligns with the porte9 in the casingV Cgthe port 4 e9 communicates (see Fig. 5) with anannuf lar recess e14 formed in the facingfofthe main casing A; and thesaid recess'eu com,- municates by a passage-way e leading to avpassage-way e18 formed in -the centre ofthe"v coreas, said passage-waycommunicating with the chamber Q through 8. calibrated. @remue e",

Within thev tube E is fitted an inner tube e, the upper end of which isopen to the atmosphere, and the lower end els of which is smaller indiameter than the bore of the tube E, and iin the lower end of the.tube618 a calibrated opening e19 is provided; the larger diameter of thetube 'e5l is provided with a longitudinal groove 62 which aligns withthe port el, so that the annular space between the two tubes is put intocommunication with the port e9, and therefore by the describedconnections with the central openin e1 in the core as. t

he tube e5 fits the tube e so as to be rotatable therein' and is movedangularly 'to control the extent of port opening from the' groove e20 tothe port el", andthe tube. e5 is fixed in the desired angular positionlby a locatino' late 621 en a in with serr'ations in the head ofthe tubee5 and secured by' the bolt e22 (see Figs. 2 and 6).

The action of the 'priming device which may also be used for slowingrunning is asfollows Vhen the lnain carburetor is not in operengine, thesuction above the throttle is high with the throttle closed and thesuction effect acting through the passage-ways e, e, the annular recesse, the port e9 in the casl ing C, and the port @1 in the tube E',draws', by suction action, the fuel from the tube E into the carburetorcasing through the passageway 616 thus providing a very rich mixturepassing to the engine and this fuel sup*- ply is sutiicient to start theengine. The tube E. having been drained, the action of slow running isas follows Air passes down the tube e5 and mixing with fuel enteringthrough the jet e3 passes up the annular space between the tubes E ande5 and the groove 62, and so to the engine through the .ports ew, e",annular groove e, passage-way e, and central passage-way Ke, the mixturebeing thoroughly atolnized and usually of the` correct proportion.

Should, however, the mixture be too rich for slow running, the tube e5is moved to a small extent angularlv so that the groove e 2 iscomparatively sealed off from the ports e and e9; the depression in theannular space between the tubes E and e5 is therefore reduced and lessfuel is supplied to the engine. The mixture strength can therefore beadjusted for slow running conditions by the angular adjustment of thetube e5.

The opening el at the bottomof the tube ,the throttle is opened fornormal-running fuel from the depression chamber B is drawn 'y throughthe passage-way a4 into the interior qof the throttle, ,and this puts,the'slow runring' device outy ofy action since the main jet stream nowdraws air downwardly through the opening elbeca'use of the greatersuction in the venturi than atport'ew.. l;

An adjustable throttle stoln (see Figs?,

and `6)"is to'regula'te the 'idling speed of the engine, thismay consistof a lug jl on .the boss J' which able screw je; l Referring nowto thefuel-ratio correcting engages with the adjustdevice F ;-the lower end ofthe tubeF is screw threaded' at f2 andscrews into a cor` respondingtapped portion of a suitable bore 1n the casing C, fornnng a verticalex- `tension of the passage-way f1; at the lower endy of the tube F acalibrated opening -f3 beingformed. The bore in the casing C in whichthe tube F .fits is enlarged so" as to form an enclosed annular space f@round the outside of the tube F', and this space communicates through aport and passage-way f5 with the depression chamber B (see Fig.

5) the annular recess f also communicates through a port f7 with theinterior of ap plug f8, rotatable in a suitable bore in the casing Cabout a horizontal axis by means of a lever 7' actuated by a Bowden wiredevice fla connected to a. casing f (see Figs.

3 to 6). The plug may be screw threaded and tit a screw-threaded bore orit may bc plain and tit a plain bore. A retaining screw f1 is employedto engage a groove in the lug.

The bore of the plug fs is provided with a lateral port fu, which by theoperation of the lever ff?, may be brought more or less into alignmentwith the air port'. f.-2..\-j:.i1n" the casingC, the degree of' portopening being dependent upon the angular position of the plug f8, inthis way the quantity of air entering the annular space f6 and from thelatter through the port f5 to the depression chamber B may becontrolled. f .j e

The action of the carburetor is as fob lows Assumingthe throttle K, K tobe slightly raised from its seat am so as tov afford a` narrowventuri-like constriction for theair drawn through the casing A by theengine suction, the depression at the ports k will v lows, therefore,that for all normal condiv ti'onsof engine runnmgthe a1r-fuel ratio 1spression in the cham The depression in the chamber Q is thus maintainedat a suitable value and is transmit-ted through the ports 7c* to theupper part or expansion chamber Q formed in the interior of fthethrottle.. This depres' sion is thence transmitted through the bore f ofthe plug 'as and passage-way at to the depression-chamber B, and as thedepression chamber is supplied with afregulable amount of air throughthe port f, the devalue than that existing in the diffuser chamber Q.The depression in the chamberA B communicates through the jet b1 andpassage-way b2 with the nozzle D, thus causing va flow of fuel to bedrawn through thel expansion chamber Q into the diffuser chamber Qwhere, before passing out through the ports 705 into the main airstream. it is thoroughly mixed with air entering between 7a2 land 71,1.

It will further be noted that fuel passing through the nozzle b1 isdiffused with 'air entering the depression chamber through the port f5and as ,the latter .air is controlled by the correcting device, thecorrect mixture for a predetermined position of the throttle can bedetermined, and when this is done I find that for any other position-ofthe throttle the apparatus will maintain this correct proportion.

-If now the throttle be raised to a higher position,say half its' range,the depression acting at the ports kf' will be reduced'in consequence ofthe reduction of the constriction-on the air stream and the reduced ve-.llocit'y Vof the latter` and for this reason the depression -in'thediffuser chamber Q would jalsotend to be reduced were it not for thefactv that as the throttle rsesthe joint action.. of the part 7a2 andthe partit1 results in the -closingof'th,e end opening'to the diffuserchambenQ, the-effect ofwhich increases the depression in the diffuserchamber to the extent necessary for thc correct flow of fuel to theincreased air flow.

-lVhenthethrottle is raisedto the full- .open position lthe part 702.practically closes .the end opening tothe diffuser chamber, thedepression then bem'g -a maximum. It fol.-

maintamed 1n correct proportion. '-1

In order to meet all the'k demands required in internalfcoi'nbustionengines under lvarious conditions. for instance when themotorv er B will be of lower y vehicle is climbing a` steep hill, andthe speed is reduced by reason of excess load, when there will be areduction of air velocity through the carburetor with a. consequentreduction of depression with fixed throttle; the flow of liquid underVariable pressure does not vary inthe same Way as the flow of air undervariable pressure, and the mixture in such cases would tend' tobecomeweak and the engine lrapidly loses power;

this defect is 'overcome bythe operation,

either automatically-or by hand, of the mixture correcting'device F.. j

The action of thisdevice is as follows y lVhen the carburetor is ina'slow running' position the fuel level in the float chamber rises to aheight'- just below that of the nozzle b1 inthe depression chamber B,the

main jet. D is therefore submerged, andthe fuel rises in the passageway7@ sealing the port f3 in the tube F., When the throttle is more fullyopened, the depressionformed in the chamber B is such that the fuellevel in the passage-way f1 and the passage-ways b2 is lowered to thelevel-of the orifice of the jet D; the passage-way f1 is nowl clear offuel, and air enters through the calibrated orifice f3 and is diffusedwith the fuel passing from the jet D with the resulting reduction ofdepression at D.

As a consequence, the amount of air passing through the tube f1 issufficient to ensure the correct amount of fuel passing when the engineis running at full throttle with normal revolutions and load. Had it notbeen for this correcting device: the amount of fuel would be too largefor engine requirements of normal revolutions and f? actuated by aBowden Wire or any other 'suitable transmission means under the controlof the driver, 1may .be'made to .control the admission ,ofI airto theannular space 'f and thus through the port and passageway f5 to .thedepression chamber B. For instance, the port f may be closed altogether,in which case the mixture would be very rich; or it maybe opened to suchan'y extent as to render the depression in the chamber B negligible, andlthis may'be done when it is desired'jto apply an air-brake to theEengine of a motor vehicle descending hills, andA thereby effectingeconomy in fuel consump tion, under. such conditions. f

As is well known an internal combustion engine requires a richer mixtureuntil it 'becomes hot'enough to run efiicientlyafter which the mixtureof fuel and air `,can be appreciably weakened; when therefore thecorrecting device isnot. operated by hand.

automatic means may be employed, a suitable form of which is shown inFigs. 2^ and 2B, the construction of which is as follows The'plug f8 andits lever ff are removed, and are replaced by a threaded sleeve m1 whichcloses the port fn, and the boreI of which communicates with the portf7; the bore of the sleeve m1 is connected by a flexible tube m2 to thethreaded end m3 of an air-control valve casing m4, in which is formed avalve seating m5; air admission through this seat being controlled by avalve p1 actuated by any suitable formI of thermo'- stat control device.In the drawings the valve p1 is actuated by a thermostat P whichcomprises an extensible tube p2 filled with air or other suitable mediumwhich-is imprisoned therein; one end of the tube p2 is connected tothethermostat casing by thel bolt p3, and the free end of the tube isconnected by a rod p4 to the Valve p1. The casing m4 can be initiallyadjusted relatively to the valve p1 by screwing it on or od the screwedend of ma and it is fixed in position by means of the nut m".

The thermostat is located in respect to the engine, say in the crankcasing, so that the temperature of the fluid in the thermostat issupplied through the port f5 to the depression chamber B; the mixturesuppliedto the engine is therefore rich enough to ensure easy starting.

As theengine temperature rises, heat is communicated to the extensibletube p2, whereupon the tube p2 extends and opensthe valve admitting airthrough the valve seating m5, flexible tube mi., port f7 and port f5 tothe depression chamber B, 'the effect of which is to gradually weakenthe mixture until when the engine is sufficiently hot it is operatedefficiently by a suitable mixture.

The setting of the valve p1 is such as to supply the right amount of airto the depression chamber B to ensure the correct air-petrol ratio, andthis adds to the economy7 and 'efficient running of the engine.

The maximum opening of the valve p1 is limited in any convenient manner,say by an adjustable screwed plug p5 engaging with the collar p, so thatshould the engine become unduly hot the mixture strength is not iabnormally affected.

While I refer to the substitution of the sleeve m1 for the plug f8,obviously the plug and the sleeve may be located in different seatingslarranged to communicate with l A The arrangement 1 described is found.to give excellent results', but the details of construction may ofcourse be modified according to the size and duty of the carburetor.

Having now fully described my invention, I decla-re that what I claimand desire to secure by Letters Patent is l. In a carburetor, incombination, a main casing having a bore one end of which forms thecarburetor outlet, and the other end of which opens to the atmosphere, aconstriction in said bore, a hollow throttle axially movable in saidbore and controlling the air flow through the annulus between the throttle and the said constriction, a fixed main fuel conduit connected tothe fuel supply, 'a fixed cylindrical sleeve at the forward end of thethrottle and into the interior of which the fixed conduit opens and withwhich the forward end ofthe throttle makes a slidingjoint, aspiratingports in the wall of the throttle the extent of opening of which isregulated by axial movement of the throttle, a perforated partitiondividing the interior of -the throttle'into two chambers, one anexpansion chamber into which the main fuel conduit leads and the other adiffuser chamber, means for controlling the admission of air through therear 'end of the throttle which reduce the area for the admission ofsaidair as the throttle is opened, and means for axially moving thethrottle.

2. In a carburetor, in combination, -a main casing having a bore one endof which forms the carburetor outlet, and the other end of which 'opensto the atmosphere, a constriction in said bore, a hollow throttleaxially movable in said bore and controlling the air flow through theannulus between the throttle and the said constriction, a fixed mainfuel conduit connected to the fuel supply, a

fixed cylindricalr sleeve at the forward end l of the throttle and intothe interior of which the fixed conduit opens andwith which the forwardend of the-throttlemakes a sliding joint, aspirating ports in thewall ofthe throttle the extent of opening of which is regulated by axialmovement of the throttle, a fixed bulbous choke core located in the mainbore of the carburetor casing, in which theI main fuel conduit islocated and by which the cylindrical sleeve isv carried, andmeans forreducing the admlssion of rair through the rear end of thethrottle assaid throttle opens, substantially as described,

3. In 'a carburetor, in combination, a main casing having a bore one endof which forms the ycarburetor outlet, and the other end of which opensto the atmosphere, a constriction in said bore, a hollow throttleaxially movable in said bore and controlling the air iiow through theannulus between the throttle and the said constriction, a fixed mainfuel conduit connected to the fuel supply, a fixed cylindrical sleeve atthe forward end of the throttle and into the interior of which the fixedconduit opens and with which the forward end of the throttle makes asliding joint, aspirating ports in the wall of the throttle the extentof opening of which is regulated by axial movement of the throttle,starting' means comprising an auxiliary conduit connected with the fuelsupply andthe throttle which reduce the area for thev admission of saidair as the throttle is opened, and means for axially moving thethrottle.

4. In a carburetor, in combination, a main casing having a bore one endof which forms the carburetor outlet, and the other end of which opensto the atmosphere,` a constriction in said bore, a hollow throttleaxially movable in said bore aiid controlling the air ow through theannulus between the throttle and the. said constriction, a fixed mainfuel conduit connected to the fuel supply, a xed cylindrical sleeve atthe vforward end of the throttle and into the interior of which thefixed conduit opens and with which the forward end of the throttle makesa sliding joint, aspirating ports in the wall of the throttle the extentof opening of which is regulated by axial movement of the throttle,starting means comprising an auxiliary conduit having its outlet end atthe outlet end of the bore of the main casing, a calibrated openingconnecting said auxiliary conduit with the main fuel conduit, a tubehaving an elongated port communicating with the auxiliary conduit andhaving also an opening communicating with the fuel supply, a second tuberotatably mounted in the first tube and having its interior open toatmosphere, said rotating ltube having an opening communicating itsinterior with thel space between the tubes, said inner tube having agroove on its exterior connecting said the carburetor outlet, and theother end of f which opens to the atmosphere, a constriction .in saidbore, a hollow throttle axially movable in said bore and controlling theair flow through the annulus between the throttle and the saidconstriction, a fixed main fuel conduit connected to the fuel supply, afixed cylindrical sleeve at the forward end of the throttle and into theinterior of which the fixed conduit opens and with which the forward endof the throttle makes a sliding joint, aspirating ports in the wall ofthe throttle the extent of opening of which is regulated by axialmovement of the throttle, means for controlling the supply of air to therear end of the throttle comprising a turned in lower end of thethrottle and a ixedconed part cooperating therewith, the forward end ofsaid coned part being of larger diameter than the rear end and means foroperating vthe throttle. i

6. In a carburetor in combination a main casing having a bore, one endof which forms a carburetor outlet, an atmosphere port, a fixed mainfuel conduit connected to a fuel supply, al depression chamber connectedto the main fuel conduit, av fuel nozzle inthe said chamber, a submergedjet connected to the fuel supply,.a conduit between said jet and saidnozzle, a regulable opening for the admission of air to 'said chamber,a' vertical tube the upper end ofwhich is open to the atmosphere, acalibrated opening in the lower endv of said tube, and a conduitconnecting the said calibrated opening to the conduit connectingthesubmerged jet to the nozzle in the depression chamber.

7 In a carburetor', in combination, a main casing, an axially movablethrottle, a perforated diaphragm in the throttle dividing it into anexpansion chamber and a diffuser chamber, a depression chamber connectedto the expansion chamber, a nozzle in the depression chamber connectedto the fuel supply, a regulable air inlet. to the depression chamber,aspirating ports in the diffuser chamber, the extent of opening of whichis controlled by movement --of the throttle, means for controlling thesupply of air to the diffuser chamber in accordance with the extent ofopening of the throttle, and means for moving the. throttle.

In witness whereof I have hereuntoy set my hand.

r ALBERT S. HODGSON.

